The group with TTR less than 70% had an ischemic stroke rate of 1.5 per 100 patient-years while taking warfarin and 2.0 per 100 patient-years after switching; for TTR less than 65%, the rates were 1.9 (before) and 1.6 (after); and for TTR less than 58%, they were 2.1 and 1.6. The gene discussed is TTR; the disease is ischemic stroke.